Pyrazole derivatives

ABSTRACT

New ultraviolet light-absorbing compounds of the formula ##SPC1## 
     In which 
     R 1  is a substituent, e.g. alkyl, 
     R 2  is a substituent, e.g. alkyl, 
     R 3  is hydrogen or a substituents, e.g. alkyl, 
     n is 1, 2 or 3, and 
     R is an n-valent, optionally substituted benzene radical, or a 1- or 2-valent naphthalene or heterocyclic radical, 
     Which are producible by known processes. 
     Such compounds are useful as stabilizers of organic materials, particularly plastics materials, against the degrading action of ultraviolet light and can be either applied as a coating on the organic material, or incorporated therein.

The present invention relates to a class of novel pyrazole derivativeswhich are useful as stabilizers of organic materials against the adverseeffects of ultraviolet light.

Accordingly, the present invention provides a class of compounds of theformula I, ##SPC2##

in which

R₁ is a C₁₋₂₂ alkyl radical, a C₅₋₁₂ cycloalkyl radical, a C₆₋₁₂cycloalkyl-alkyl radical, a C₇₋₁₂ aralkyl radical, of which the alkylradical and the alkyl moiety of the cycloalkyl-alkyl radical areuninterrupted or interrupted by 1 or 2 sulphur atoms or by --COO--, andthe aryl nucleus of the aralkyl radical is unsubstituted or substitutedby a hydroxyl group and/or 1 or 2 C₁₋₁₂ alkyl radicals, or a phenylgroup, unsubstituted or substituted by one or more substituents selectedfrom 1 or 2 halogen atoms, a cyano group, a hydroxyl group, 1 or 2 C₁₋₁₂alkyl radicals, 1 or 2 C₁₋₁₂ alkoxy radicals, a phenyl group and theradicals R₄ --O-- and R₄ --SO₂ --, wherein R₄ is a phenyl group,unsubstituted or substituted by 1 or 2 C₁₋₈ alkyl radicals,

R₂, independently of R₁, has one of the significances of R₁, or is acyano group or the radical --COOR₅, wherein R₅ is a C₁₋₁₂ alkyl radical,a C₅₋₁₂ cycloalkyl radical, a C₆₋₁₂ cycloalkyl-alkyl radical or a phenylgroup, unsubstituted or substituted by a hydroxyl group and/or 1 or 2C₁₋₈ alkyl radicals,

R₃ is a hydrogen atom or one of the significances of R₁, --COR₁ or--COOR₅, j

n is 1, 2 or 3, and

R, when n is 1, is a phenyl group, unsubstituted or substituted by atotal of up to 3 substituents selected from 1 hydroxyl group, 1 to 3halogen atoms, 1 phenyl group, 1 benzyl group, 1 phenoxy group, 1 to 3alkyl radicals each containing 1 to 8 carbon atoms and the sum of thecarbon atoms not exceeding 12, and 1 to 3 alkoxy radicals eachcontaining 1 to 22 carbon atoms and the sum of the carbon atoms notexceeding 22, or a monovalent naphthalene radical, or a monovalentradical of thiophene, benzothiophene, dibenzothiophene, furan,benzofuran or dibenzofuran, and when n is 2, is a phenylene group,unsubstituted or substituted by a C₁₋₄ alkyl radical and/or a halogenatom, or a divalent naphthalene radical, or a divalent radical ofthiophene or dibenzofuran, and when n is 3, is a 1,3,5-trivalent benzeneradical.

A preferred group of ultraviolet stabilizing compounds of the formula Iare those of the formula Ia, ##SPC3##

in which

each of R₁ ' and R₂ ' , independently, is a C₁₋₈ alkyl radical or aphenyl group, unsubstituted or substituted by up to 4 substituentsselected from a hydroxyl group, a halogen atom and 1 or 2 C₁₋₄ alkylradicals,

R₃ ' is a hydrogen atom or one of the significances of R₁ ' or --COR₁ ',

n' is 1 or 2, and

R', when n is 1, is a phenyl group, unsubstituted or substituted by atotal of up to 3 substituents selected from 1 hydroxyl group, 1 C₁₋₆alkoxy radical and 1 to 3 C₁₋₆ alkyl radicals, the sum of the carbonatoms of these substituents not exceeding 12, and when n is 2, is aphenylene group, unsubstituted or substituted by a C₁₋₄ alkyl radical;

A preferred group of ultraviolet stabilizing compounds of the formula Iaare those of the formula Ib, ##SPC4##

in which

each of R₁ " and R₂ " , independently, is a C₁₋₄ alkyl radical or aphenyl group, unsubstituted or substituted by a halogen atom,

R₃ " is a hydrogen atom or one of the significances of R₁ ' , ashereinbefore defined,

n' is 1 or 2, and

R", when n is 1, is a phenyl group, unsubstituted or substituted by atotal of up to 3 substituents selected from 1 hydroxyl group, 1 C₁₋₄alkoxy radical and 1 to 3 C₁₋₄ alkyl radicals, the sum of the carbonatoms of these substituents not exceeding 10, and when n is 2, is aphenylene group;

A preferred group of ultraviolet stabilizing compounds of the formula Ibare those of the formula Ic, ##SPC5##

in which

R₁ " , r₂ " and R₃ " are as previously defined, and

R"' is a phenyl group which is substituted in the ortho- orpara-position by a hydroxyl group and by 1 or 2 tertiary butyl groups inmeta-position(s) adjacent to the hydroxyl group, or by a C₁₋₄ alkoxyradical.

In this specification, an alkyl radical, if not otherwise stated, may beprimary, secondary or tertiary, and may be derived from a naturalaliphatic hydrocarbon which is branched in any way. Examples of primaryalkyl radicals are methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyland unbranched primary C₇₋₂₂ alkyl radicals, of secondary alkyl radicalsare isopropyl and 2-butyl, and of tertiary alkyl radicals are tertiarybutyl and 2-methyl-2-butyl. Examples of alkyl radicals with theappropriate number of carbon atoms serve to exemplify the alkyl moietiesof alkoxy radicals.

Examples of cycloalkyl radicals are cyclopentyl, cyclohexyl, cycloheptyland cyclododecyl, and of cycloalkyl-alkyl are cyclohexyl-methyl and2-cyclohexyl-ethyl. To exemplify aralkyl radicals envisaged in thisspecification may be mentioned benzyl and 2-phenylethyl.

By the term `halogen` is meant fluorine, chlorine or bromine, of whichchlorine is the preferred halogen atom.

Alkyl radicals or cycloalkyl-alkyl radicals whose aliphatic chains areinterrupted by 1 or 2 sulphur atoms or by --COO-- are exemplified by CH₃--S--CH₂ CH₂ --, C₁₂ H₂₅ --S--(CH₂)₈ --, C₂ H₅ OCOCH₂ --, C₁₂ H₂₅ OCOCH₂-- and C₈ H₁₇ OCOCH₂ --.

Examples of R₁ when signifying a substituted phenyl group are ##SPC6##

and examples of R are ##SPC7##

In the above formulae I, Ia and Ib, n or n' is preferably 1 and thepreferred meaning of R,R' and R", respectively, is a phenyl group whichis substituted in the ortho- or para-position by a hydroxyl group and by1 or or 2 tertiary butyl groups in meta-position(s) adjacent to thehydroxyl group, or by a C₁₋₄ alkoxy radical.

The present invention also provides a process for producing a compoundof the formula I, which comprises reacting a compound of the formula II,##SPC8##

in which

R₁, r₂ and R₃ are as defined above,

with a compound of the formula III,

    r -- (cooh).sub.n                                          III

in which

R and n are as defined above,

or a functional derivative thereof.

The reaction between the compounds of the formulae II and III isadvantageously effected in a reaction-inert organic solvent, in whichthe reagents may be dissolved or even suspended, preferably by heatingwithin the temperature range 20° to 110°C. Suitable solvents for thereaction include benzene, xylene, cymene, diphenylether, tetrahydrofuranand dioxan.

When an acid chloride is used as the functional derivative of a compoundof the formula III, this being the preferred functional derivative,hydrogen chloride is liberated in the reaction. In such a case, anacid-binding agent, e.g. lime, an alkali metal carbonate or bicarbonate,pyridine, a trialkylamine or a dialkylaniline, is preferably present inthe reaction medium. Additionally it is preferable to effect thereaction in the absence of humidity.

The present invention further provides a method of stabilizing anorganic material against the action of ultraviolet light comprisingtreating the organic material with a compound of the formula I, ashereinbefore defined. By the term "treating" as used herein, is meanteither incorporating into the body of the organic material, or surfacecoating the organic material, in a manner known per se. Thus the methodof the invention comprises treating the organic material, either by wayof mixing the compound of the formula I with the organic material, or byway of coating the compound of the formula I as a protective layer onthe surface of the organic material. Through its ultravioletlight-absorbing property, the compound of the formula I, incorporated inor coated on an organic material sensitive to ultraviolet light,protects the material from the degradative action of ultraviolet light.

Suitable organic materials for such protective treatment includepolyolefins, especially polyethylene and polypropylene, polyesters,polymethylmethacrylates, polyphenylene oxides, polyurethanes,polystyrene, ABS-terpolymers, polyamides, especially nylon,polypropylene oxide, polyacrylonitrile and copolymers of theaforementioned polymers. Preferably the compounds of the formula I areused, according to the method of the present invention, to stabilizepolypropylene, polyethylene, polyester, polyamide, polyurethane,polyacrylonitrile, ABS-terpolymers, terpolymers of acrylic ester,styrene and acrylonitrile, and copolymers of styrene and acrylonitrileand of styrene and butadiene. As well as the aforementioned syntheticmaterials, natural materials, e.g. rubber, cellulose, wool and silk, maybe stabilized by a compound of the formula I according to the method ofthe present invention.

The materials to be protected according to the method of the presentinvention may be in the form of plates, rods, coatings, sheets, fibres,strips, films, granules, powders and other solid forms, or in solutions,emulsions or dispersions.

The incorporation into or coating of the particular organic material tobe treated with a compound of the formula I may be effected by knownmethods. In one embodiment of the method of the invention, the organicmaterial, for example in granular form, is intimately mixed with one ormore compounds of the formula I, for example in a kneader or othersuitable mixing device, and is subsequently extruded to its final form.Examples of the forms taken by the product of such a process are sheets,loops and filaments. In another embodiment, textile threads or fabricsare treated with one or more compounds of the formula I in an aqueousbath containing the stabilizer in dispersion. Textiles of polyethyleneterephthalate and cellulose acetate are particularly suitable for suchprocessing.

Synthetic materials do not necessarily have to be completely polymerizedor condensed before treatment with compounds of the formula I, sincemonomers of prepolymers may be mixed with such stabilizers andthereafter converted to products in their final forms by condensation orpolymerisation.

The compounds of the present invention are not only employable for thestabilization against ultraviolet light of clear films, but may also beused to stabilize opaque, semi-opaque or translucent organic materialswhose surfaces are susceptible to degradation by ultraviolet light.Examples of such latter materials are foamed plastics, opaque films andcoatings, opaque papers, transparent and opaque dyed plastics,fluorescent pigments, automobile and furniture polishes, creams andlotions.

The amount of stabilizer of the formula I suitably employed in themethod of the present invention will naturally depend on the mode ofapplication, the particular compound of formula I employed, and thenature and form of the organic material to be treated. However, ingeneral satisfactory results are obtained when the amount of stabilizerof the formula I employed is between 0.01 and 5%, preferably between0.05 and 1%, of the weight of the organic material to be treated.

The stabilized organic material may only contain, as ultravioletstabilizer, one or more compounds of the formula I, or it mayadditionally contain other adjuvants for improving its properties. Suchother adjuvants may be, for example, further stabilizers orco-stabilizers against the adverse effects of heat, oxygen orultraviolet light, and they may belong to quite different chemicalclasses to that of the compounds of formula I.

A further feature of the present invention comprises the organicmaterials which contain one or more compounds of the formula I asstabilizers against the adverse effects of ultraviolet light. Inaccordance with the methods hereinbefore described for the production ofsuch stabilized organic materials, the latter may contain from 0.01 to5% by weight of one or more compounds of the formula I as stabilizingagent, or preferably from 0.05 to 1% by weight.

In the following Examples, which illustrate the compounds of the presentinvention, processes for their production and methods of theirapplication, the parts and percentages are by weight and thetemperatures are in degrees centigrade. The indicated structures areverified by microanalysis and spectroscopic analysis.

EXAMPLE 1

23.6 Parts of 1,3-diphenyl-pyrazol-5-one and 8 parts of pyridine areadded to 200 parts of toluene. 26.8 Parts of3,5-di-tert.-butyl-4-hydroxybenzoyl chloride are added in portions tothe solution whilst stirring, at 20°C, and the solution is left to reactfurther at this temperature until no pyrazolone is detectable. Themixture is then washed with water, the organic phase is separated anddried, and the solvent distilled off. The residue is crystallized fromethanol. The compound having a melting point of 150° to 151°C of formula##SPC9##

is obtained.

EXAMPLE 2

11.8 Parts of 1,3-diphenyl-pyrazol-5-one and 6.0 parts of triethylamineare added to 100 parts of toluene. 9.8 Parts of 4-tert.-butyl-benzoylchloride are added in portions to the solution whilst stirring, at 60°C,and the solution is left to react further at this temperature until nopyrazolone is detectable. The mixture is then washed with water, theorganic phase is separated, dried and the solvent distilled off. Theresidue is crystallized from hexane. The compound having a melting pointof 106° to 107°C of formula ##SPC10##

is obtained.

The following compounds, which are listed in Table 1, are produced in asimilar manner.

                                      TABLE I                                     __________________________________________________________________________     ##STR1##                                                                     No.  R.sub.1 R.sub.2                                                                              R.sub.3   R         M.p.°C                         __________________________________________________________________________          ##STR2##                                                                             CH.sub.3 --                                                                           ##STR3##                                                                                ##STR4## 215-16                                2                                                                                   ##STR5##                                                                             CH.sub.3--                                                                            ##STR6##                                                                                ##STR7## 170-72                                3    CH.sub.3 --                                                                           CH.sub.3 --                                                                          H                                                                                        ##STR8## 139- 40                               4                                                                                   ##STR9##                                                                             CH.sub.3 --                                                                          H                                                                                        ##STR10##                                                                              152-54                                5                                                                                   ##STR11##                                                                            C.sub.3 H.sub.7 --                                                                   H                                                                                        ##STR12##                                                                              93-95                                 6                                                                                   ##STR13##                                                                            CH.sub.3 --                                                                          H                                                                                        ##STR14##                                                                              140-141                               7                                                                                   ##STR15##                                                                            CH.sub.3 --                                                                          H                                                                                        ##STR16##                                                                              81-82                                 8                                                                                   ##STR17##                                                                            CH.sub.3 --                                                                          H                                                                                        ##STR18##                                                                              132-133                               9                                                                                   ##STR19##                                                                            CH.sub.3 --                                                                          H                                                                                        ##STR20##                                                                              86-88                                 10                                                                                  ##STR21##                                                                            CH.sub.3 --                                                                          H                                                                                        ##STR22##                                                                              130-131                               11                                                                                  ##STR23##                                                                            CH.sub.3 --                                                                          C.sub.2 H.sub.5 --                                                                       ##STR24##                                                                              144-145                               12                                                                                  ##STR25##                                                                            CH.sub.3 --                                                                          --C.sub.4 H.sub.9 (n)                                                                    ##STR26##                                                                              134-135                               13                                                                                  ##STR27##                                                                            --COOC.sub.2 H.sub.5                                                                 H                                                                                        ##STR28##                                                                              63-64                                 14                                                                                  ##STR29##                                                                             ##STR30##                                                                           H                                                                                        ##STR31##                                                                              135-136                               15                                                                                  ##STR32##                                                                             ##STR33##                                                                           H                                                                                        ##STR34##                                                                              120-121                               __________________________________________________________________________     ##STR35##                                                                       In a similar manner, the following compounds were also produced        

Non-stabilized polypropylene is mixed intimately with 0.5% of thecompound of Examples 1, 2 and Nos. 1, 6 and 7 of Table 1 on a rollermill at 180°C and is processed to form sheets of 0.3 mm thickness. Theseare tested in the climate test to demonstrate their resistance againstthe action of ultraviolet light by the De La Rue method. The test iscarried out at 40°C, with 75% relative humidity and strong ventilation,using 16 Philips Sunlamps and 16 Philips Blacklamps. Stabilizedpolypropylene shows considerably better results than non-stabilizedpolypropylene. Non-stabilized polyvinyl chloride and polyvinyl chloridecontaining 0.5% of the compound No. 1 of Table 1 are tested similarly inthe climate test.

Similar results may be obtained for polyethylene, ABS-terpolymers,polyethylene terephthalate, cellulose acetobutyrate, polyamide 6,polystyrene, polycarbonate and polyurethane.

What is claimed is:
 1. A compound of the formula I, ##SPC12##wherein R₁and R₂, independently, are C₁₋₄ alkyl or unsubstituted phenyl, and R isphenyl monosubstituted in the ortho- or para-position by a hydroxy groupand mono- or disubstituted in the meta-position(s) by a tertiary butylgroup, wherein the tertiary butyl group or at least one of the twotertiary butyl groups is adjacent to the hydroxy group, or phenylmonosubstituted by C₁₋₄ alkoxy.
 2. A compound according to claim 1, ofthe formula, ##SPC13##
 3. A compound according to claim 1, of theformula, ##SPC14##
 4. A compound according to claim 1, of the formula,##SPC15##
 5. A compound according to claim 1, of the formula, ##SPC16##